Self-priming centrifugal pump



July 24, 1956 H. E. RUPP 2,755,743

SELF-PRIMING CENTRIFUGAL PUMP Filed 001.. 11, 1954 2 Sheets-Sheet l CE /0 g INVENTOR. HE/IBEET E- EUPP A TTOENEYS United States Patent 9 SELF-PRINIING CENTRIFUGAL PUlVlP Herbert E. Rupp, Mansfield, Ohio, assignor to The Gorman-Rupp Company, Mansfield, Ohio, a corporation of Ohio Application October 11, 1954, Serial No. 462,150

4 Claims. (Cl. 103-113) This invention relates generally to centrifugal pumps and is particularly concerned with a self-priming centrifugal pump which has a straight open direct intake passage into the eye of the impeller and in which the intake lacks both check valves and liquid supply traps, and the discharge lacks a check valve, thereby reducing the pump to the simplest form yet attained.

This invention permits the draining of the pump to the lowest point of the intake when the pump ceases operation and the liquid that is retained in the discharge chamber below the point of drainage is again drawn into the impeller chamber when the pump is started up later on and of sufficient amount to again cause the pump to function without the supplying of liquid from another source. The results are, due to the absence of check valves or a supply chamber in the intake, at more efiicient pump which lends itself to less costly construction due to the simplicity of the parts that make up the pump. The invention lends itself to pattern and core work of the simplest type, thereby expediting the manufacture of the pump. The foregoing not only reduces the initial cost of the pump but also the cost of maintaining the pump in operation. This is especially true in chemical pumps in which valves, etc., are expensive items of maintenance.

Self-priming centrifugal pumps, as constructed heretofore, have included various means of retaining sutficient liquid in the impeller chamber for successful operation. The normal construction required the use of an enlarged and elevated intake to retain sufficient liquid in case of a backfiow when the pump is shut down, to feed liquid into the impeller chamber in sufiicient amount to submerge the impeller and liquid seal it when the impeller is started rotating, or a check valve is imposed in the intake to retain the liquid in the impeller and discharge chamber. Either construction detracts from the efliciency of the, pump, especially so when the pump is working at a high suction lift, which working condition commands a self priming centrifugal pump if a centrifugal pump is to be used.

The methods of making a centrifugal pump self-priming are quite well known in the art, and all of the methods embody the invention of initially charging the pump with liquid that is to be pumped; the construction of the pumpis such that this charging liquid receives air or gases from the impeller as it rotates and a separating means must be provided to separate the air or gas from the liquid and continually bringing air-free liquid into the proximity of or into the impeller. This bringing of liquid into the proximity of or into the impeller may be at any point from the outer periphery to the intake of the impeller. The present invention can embody the entire scope of bringing the air-free liquid into the presence of the impeller and will be better understood by those skilled in the art from the following description and the drawings which accompany and form a part of this specification and in which:

Fig. 1 is a vertical, central, sectional view taken. through Patented July 24, 1956 ice 2 a pump embodying the present invention and looking toward the intake side of the impeller housing;

Fig. 2 is a vertical, sectional view of the pump of Fig. 1 taken on line 2-2 of that figure;

Fig. 3 is a hoizontal, sectional view of the pump of Fig. 1 taken on line 3-3 of that figure;

Fig. 4 is a fragmentary, sectional view similar to a portion of Fig. l but showing a modified form of the invention;

Fig. 5 is a central, vertical, sectional view showing another modified form of the invention;

Fig. 6 is a vertical, sectional view taken on line 6-6 of Fig. 7 and showing another modified form of the invention; 1

Fig. 7 is a sectional view taken, on line 7-7 of Fig. 6;

Fig. 8 is a sectional view taken on line 8-8 of Fig. 7; and

Fig. 9 is a view similar to Fig. 7 but showing a modified form of construction.

The pump shown in Figs. 1, 2 and 3 comprises a pump casing 1 having a pumping chamber 2 at one end thereof and a combined discharge and separating chamber 3 extending horizontally therefrom to the opposite end of the casing. A liquid outlet pipe 4 leads out from the upper part of chamber 3 and an intake or inlet pipe 5 is connected to a tubular projection in the front side wall 6 of the casing 1. The rear side of the casing opposite to wall 6 is provided with an opening through which the impeller may be inserted or removed and this opening is fitted with a cover or rear plate 7. An impeller shaft 8 extends through plate 7 into casing 1 and at its inner end carries an impeller comprising a back plate 9 and a plurality of vanes 10 positioned at right angles to the face of the plate 9 and spiraling outwardly from adjacent the center of the plate with their outer or tip ends projecting beyondthe periphery of the plate 9. The space at the center of plate 9 and between the inner ends of the vanes It is known as the impeller intake or eye and is opposed to the inlet pipe 5.

The pumping chamber 2 may be thought of as comprising two parts or chambers. The chamber defined by the front and rear sides 6 and 7 of casing 1 and traversed by the vanes 10 may be known as the impeller chamber while the space at. the periphery of the impeller chamber may be known as a flow chamber. It will be noted that the impeller chamber is of greater diameter than the back plate 9 of the impeller, the solid line 11 in Fig. 1 and line 12 in Fig. 2 indicating the periphery of impeller chamber.

The flow chamber 15 is smallest at one side of an inwardly extending part 16 of the top wall of casing 1 where the tips of the vanes pass close to that wall 16,. and increases in cross-sectional size as it continues around the impeller chamber and opens into a discharge passage 17 on the opposite side of wall 16. The outer wall of chamber 15, for a large part of its length, is an end wall of casing 1 and for the remainder of its length is a partition or cross wall 20 which extends from that end Wall below and at one side of the impeller, across the space between the side walls of casing l and upwardly at one side of the impeller chamber and a short distance away from wall 16 to form, with wall 16 and the sidewalls of the casing, the discharge passage 17 through which liquid may be pumped from the impeller chamber into the combined discharge and separating chamber 3. It will be noted that wall 20 may be considered as a curving continuation of the curving end wall of the casing from below the impeller to the discharge passage. It will also be noted that the cross-sectional area of the throat or inlet end of the discharge passage 17 in a horizontal plane through the tip of wall 16' is only a little. larger than the greatest cross-sectional area of the flow chamber, that the open end of passage 17 is some distance above the tip of wall 16, that the cross-sectional area of passage 17 progressively increases from its beginning at the tip of wall 16 to its discharge end, and that when this throat is filled with water it effectively seals theimpeller chamber against the ingress of air through the discharge passage and, slows the rate of flow of liquid therein.

The cross wall 20 is spaced a short distance above the bottom wall of casing 1 and part 25 of the discharge and separating chamber lies between these two walls. That chamber is connected to the pumping chamber 2 by a. passage 26 formed in the front wall 6 of the casing 1. This passage 26, which may be considered as a priming passage, opens into chamber 2 where the vanes overhang or project beyond the periphery of plate 9. Passage 26 need not extend vertically as shown in Figs. 1 and 2 but may be inclined to the vertical and may even be substantially horizontal if desired.

Theinlet pipe 5 is constantly open, is valveless, is free from enlarged liquid supply chambers and, as shown in Figs. 1 to 3, opens into the pumping chamber substan-v tially coaxial with the impeller shaft. The inlet pipe may serve as a drain for the pump. When the pump is positioned with the inlet pipe extending horizontally or downwardly from the pumping chamber, the level to which liquid may drain out of the pump is defined by the lowest point of intersection of the inner surface of inlet pipe and the inner surface of the pumping chamber wall. If desired, the front wall 6 of the casing may be cut away as is shown at 27 to facilitate drainage of liquid from pipe 5 into the impeller chamber.

It will be noted that the space available for liquid within casing 1 and between the priming passage and the drainage level, as just described, is of such a size as will hold sufiicient liquid to feed into and fill chamber 2,

discharge passage 17 and priming passage 26 with liquid and thereby submerge and liquid seal the impeller when the impeller begins to rotate. Since the priming passage 26 is filled with liquid at all times when the impeller is at rest and discharge passage 17 is quickly filled with liquid after the impeller begins to rotate, and both of these passages are maintained full of liquid during rotation of the impeller, the rotation of the impeller promptly withdraws air from the intake pipe 5 and delivers it into chamber 3 and liquid is brought into the chamber 2 through pipe 5 as a result of this reduction in pressure. When the liquid so brought in fills casing 1, it passes out through pipe 4. Thus, the pump is self-priming and, without the use of a standpipe or chamber above the impeller chamber or check valves.

The pump shown fragmentarily in Fig. 4 is quite like the pump of Figs. 1 to 3, as the use of like numerals indicates. The main dilference between the pump of Fig. 4 and that of Fig. l is in the priming passage connecting the discharge and separating chamber 3 with chamber 2. In Fig. 4, the passage 26a extends directly through partition or cross wall 20 from chamber 3 into chamber 15. The operation of the pump of Fig. 4 is substantially as described above in connection with Figs. 1, 2 and 3.

The pump of Fig. 5 is quite like the pumps of Figs. 1 to 4 in structure and operation. The main ditferences are in the cross wall construction. In Fig. 5 the end wall 30 of easing 1 curves about the periphery of the impeller and merges into the bottom wall 31 of the casing. A cross wall 20a extends between the front and rear walls of the casing but does not merge into the end or bottom walls of the casing. This cross wall 20a extends from a point below the impeller and at one side of the vertical centerline thereof, around the bottom and up past one side of the impeller and defines a discharge passage 17a with the side walls of the casing and with inwardly projecting wall 16 which lies closeto the orbit of rotation of the ends of the vanes 10. In this form of the invention, the part 25a of the discharge and separating chamber, lying between cross wall 20a and bottom wall 31 4 of the casing, communicates with the chamber 3 through passage 26b which extends between Wall 20a and the end wall 39 of casing 1 and empties into the flow chamber 15 at the lower end of wall 20a. The structure and mode of operation of the pump of Fig. 5 is substantially the same as has been described above in connection with the pumps of Figs. 1 to 4, inclusive.

In the pump shown in Figs. 6 and 7, the combined discharge and separating chamber and the pumping chamber are positioned'in what might be called side-by-side relation instead of in the edge-to-edge relation of Figs. 1 to 5. The pump of Figs. 6 and 7 comprises a casing 1a having a front plate 40, an endless side wall 41 with feet 42 integral therewith to rest on and be secured to a support, an axial inlet tube 43 and a rear wall 44. The wall 44 is provided with an opening fitted with a cover plate 45 which rotatably carries an impeller shaft 8 and an impeller consisting of a back plate 9 and vanes 10. The wall 44 extends axially inwardly of the casing 1a, as at 46, and transversely of the pump axis as at 47 to form a pumping chamber designated generally at 48 and consisting of an impeller chamber part and a flow part extending therearound and opening into a discharge passage 48a formed between the side wall 41 and the radial wall 46. This passage 48:: has an outlet 48!) near the top of the casing 1a into the discharge and separating chamber 49 which is partly defined ,by front wall 40, side wall 41 and tubular wall 43 of casing 1a.

The tubular wall 43 which extends from the front Wall 49 to the transverse or partition wall 47 serves as an inlet for fluid to be pumped and is threaded as indicated at 50 for connection to an inlet pipe. An outlet pipe may be fitted either into top opening 51 or side opening 52 of the casing.

The discharge and separating chamber 49 communicates with the pumping chamber 48 through a priming passage 55 formed between the side wall 41 of casing 1a and curving cross wall 56 which extends from the throat or inlet end of discharge passage 48a down around the impeller to a point below and beyond its center of rotation.

As in the pumps of Figs. 1 to 5, the drainage level of the pump of'Figs. 6 and 7 is at the intersection of the lower inner surface of the inlet pipe 43 and the inner surface of impeller chamber wall 47 when the pipe 43 is horizontal or inclined downwardly and outwardly; and the discharge passage 48a is quickly filled and is maintained full of liquid from the supply below the drainage level when the impeller is rotated.

The pump shown in Fig. 8 is quite like that shown in Figs. 6 and 7. The main difference is in the intake pipe 60 which extends up through side wall 41a and into the discharge and separating chamber 49a where it makes a bend and opens through wall 47a into the impeller chamber. This inlet pipe 60 serves to drain liquid out of the pump to the level of the intersection of the lower inner surface of pipe 60 and the inner surface of wall 47a.

It will be understood from the foregoing disclosure that pumps embodying the present invention include a minimum number of simple parts which are relatively inexpensive to construct and easy to maintain. The casing in each instance is a simple, easy to make casting, for the patterns and cores are of simplest type.

Practically the only machining of the casing which is required is to thread it for reception of outlet and intake pipes 4 and 5 and to machine it for reception of the back plate and the impeller parts. The impeller is simple in design and comparatively inexpensive to make. The casing is small in size as compared with prior selfpriming pumps by reason of the fact that only a small volume of liquid need be retained in the casing for priming purposes. No check valves are required and the pumps are self-draining to a level at about the lower level of the impeller intake. This simplification of construction accompanies the new mode of priming which does not depend on the presence of a large amount of liquid but on a new manner of sealing the impeller chamber with a small quantity of liquid.

By the term conventional impeller as used in the claims, I mean an impeller of ordinary construction consisting, for example, of a disk-shaped back plate, a plurality of vanes disposed edgewise on the front side of said back plate and curving outwardly from the central part of the back plate to adjacent to the outer periphery of the back plate and with or without a front ring or shroud connected to the front edges of the vanes and providing an inlet at the central part of the impeller into the space between the vanes.

Several facts concerning the shape, position and arrangement of the discharge passages and the inlet conduits of the above disclosed modifications of the invention are especially to be noted.

As will be seen from the drawings, each discharge passage is a smooth continuation of the flow chamber, progressively enlarges, opens directly into the gas filled part of the discharge and separating chamber well above the surface of liquid in the latter during priming and is free from abrupt bends connecting passages and the like. The smooth continuation of the flow chamber and the freedom from bends and connecting passages is reflected directly in low resistance to fluid flow and, hence, in greater efiiciency of the pump. The progressive enlargement of the discharge passage and the fact that it discharges into a gas filled space, until the priming operation has been completed and the discharge and separating chamber has been nearly filled with liquid, is reflected in decreased velocity of flow of liquid through the discharge passage and in the absence of turbulence. The presence of tranquillity of flow, the absence of turbulence and the complete filling and sealing of the discharge passage by the liquid it is pumping eifectively prevents air from entering the pumping chamber through the discharge passage.

These structural features make possible the entirely new operation of priming with a much smaller amount of liquid than the minimum amount previously required. To put a pump embodying this invention into operation only enough liquid need be placed in the casing to insure that, when the impeller is rotating, the priming flow and discharge passages will be filled and maintained full of liquid and that the pumping chamber will contain enough liquid so that the centrifugal force applied by the impeller to the liquid in the pumping chamber will overcome the force of vacuum in the impellers interior, its eye and in the related inlet conduit.

Since the combined volume of the impeller chamber and the priming flow and discharge passage may be small in comparison with the volume of the discharge and separating chamber, the surface level of the liquid required for priming may lie below the axis of the impeller when it is at rest, and the location of that surface level may be determined as desired by suitably proportioning the volumes.

Since the casing may contain the necessary amount of liquid below the eye of the impeller, it is unnecessary to depend on the inlet conduit for performance of some part of the priming operation. Thus this invention makes it unnecessary to employ an intake conduit having a check valve, or an enlarged chamber for retaining liquid, or positioned so as to retain liquid for priming.

The shape, position and arrangement of the intake conduit in the casing is immaterial, so far as the priming action is concerned, since its only necessary function in the present apparatus is to conduct liquid into the impeller chamber. The inlet conduit may be coaxial with the horizontal impeller shaft, as shown in Figs. 1 to 8, or it may extend downwardly as is shown in Fig. 9, or it may extend in any other desired direction. When the liquid being pumped is below the pump and the pumping operation is stopped, liquid will drain out of the the lower inner surface of the conduit with the inner surface of the impeller wall through which the conduit opens; and the liquid may be siphoned out through an upwardly extending; inlet conduit to a level below the intersection of the upper inner surface of the conduit with the inner surface of the impeller wall.

By suitably proportioning the combined volumes of the impeller chamber and the priming flow and discharge passages to the volume of the combined chamber, it is possible to insure that enough liquid will be retained in the casing when the pumping operation is stopped for the subsequent priming operation. Thus it is clear that the function of the intake conduit of the present invention is merely to condut gas and liquid to the impeller chamber to permit excess liquid to flow out of the casing when the pumping operation is stopped, and that the intake conduit does not perform any part of the priming function.

The present invention is the first instance, so far as I know, in which a self-priming pump (1) would prime with only enough liquid to fill the priming flow and discharge passages and maintain them full and to provide the necessary amount of liquid. in the impeller chamber, (2) had a passage leading from the impeller chamber and discharging directly into a gas filled space in the upper part of a discharge and separating chamber during priming, or (3) had a discharge passage leading from the impeller chamber which is sealed by the liquid it is dis,- charging.

This. application is a continuation-in-part of my copending application, Serial, No. 127,304, filed November 15, 1949, now abandoned.

Having thus described the present invention so that others skilled in the art may be able to understand and practice. the same, I state that what I desire to secure by Letters Patent is defined in what is claimed.

What is claimed is:

l. A self-priming centrifugal pump comprising a easing and a partition wall therein, said casing and wall defining a pumping chamber and a combined discharge and separating chamber, a. rotatably mounted conven- I tional impeller in said pumping chamber and having an intake eye at its axis, said partition partly defining a priming passage leading from the lower part of said combined chamber into the lower part of said pumping chamber and a discharge passage leading upwardly from the pumping chamber and opening directly into the upper part of said combined chamber, said discharge,

passage progressively increasing in cross-sectional area from its inlet from the pumping chamber to its outlet and serving effectively to slow the rate of flow of liquid discharged thereinto from the pumping chamber and to seal within itself against the flow of air therethrough into the pumping chamber and an inlet conduit opening into said pumping chamber and serving, when the impeller is at rest, to drain liquid from the chambers to the level of the intersection of the lower inner surface of said conduit and the inner surface of said impeller chamber, said conduit being constantly open, valveless and free from an enlarged liquid supply chamber, the liquid-containing space in the pumping and combined chambers below said intersection exceeding the combined liquid-containing space in the pumping chamber and in said priming and discharge passages whereby, when the impeller is rotated, the pumping chamber and the priming and discharge passages will be filled with, and maintained full of, liquid and the flow of unen'trained air into the pumping chamber through either of said passages will be prevented.

2. A self-priming centrifugal pump comprising a casing having front and side walls and partly defining a combined discharge and separating chamber and having a rear wall and an interior wall partly defining a pumping chamber, said interior wall partly defining a priming passage leading from the lower part of said combined chamber into the lower part of said pumping chamber, and a discharge passage leading upwardly from the pumping chamber and opening directly into the upper part of said combined chamber, said discharge passage progressively increasing in cross-sectional area from its inlet from the pumping chamber to its outlet and serving eifectively to slow the rate of flow of liquid discharged thereinto from the pumping chamber and to seal within itself against the flow of air therethrough into the pumping chamber a rotatably mounted conventional impeller in said pumping chamber and having an intake eye at its axis, and an inlet conduit extending through said combined chamber and opening through said interior wall into the pumping chamber at the impeller eye and serving, when the impeller is at rest, to drain liquid from the chambers to the level of the intersection of the inner lower surface of the conduit and the inner surface of said interior wall, said conduit being constantly open, valveless and free from an enlarged liquid supply chamber, the liquid-containing space in the pump ing and combined chambers below said intersection exceeding the combined liquid-containing space in the pumping chamber and in said priming and discharge passages whereby, when the impeller is rotated, the pumping chamber and the priming and discharge passages will be filled with, and maintained full of, liquid and the flow of unentrained air into the pumping chamber through either of said passages will be prevented.

3. A self-priming centrifugal pump comprising a casing having front, rear and side walls and an interior wall, said walls defining side-by-side chambers, one of said chambers being a pumping chamber provided with a rotatably mounted conventional impeller having an intake eye at its axis, and the other chamber being a combined discharge and separating chamber, said interior wall partly defining a priming passage leading from the lower part of said combined chamber into the lower part of said pumping chamber and a discharge passage leading upwardly from the pumping chamber into the upper part of said combined chamber, said discharge passage progressively increasing in cross-sectional area from its inlet from the pumping chamber to its outlet and serving effectively to slow the rate of flow of liquid discharged thereinto from the pumping chamber and to seal within itself against the flow of air therethrough into the pumping chamber and an inlet conduit extending through said combined chamber and opening through said interior wall into said pumping chamber and serving, when the impeller is at rest, to drain liquid from the chambers to the level of the intersection of the lower inner surface of the conduit with the inner surface of said interior wall in the impeller chamber, said conduit being constantly open, valveless and free from an enlarged liquid supply chamber, the liquid-containing space in the pumping and combined chambers below said intersection exceeding the combined liquid-containing space in the pumping chamber and in said priming and discharge passages whereby, when the impeller is rotated,

the pumping chamber and the priming and discharge passages will be filled with, and maintained-full of, liquid and the flow of unentrained air into the pumping chamber through either of said passages will be prevented.

4. A self-priming centrifugal pump comprising a casing and a partition wall therein, said casing and wall defining a pumping chamber and a combined discharge and separating chamber, a rotatably mounted conventional impeller in said pumping chamber and having an intake eye at its axis, an inlet conduit opening into said pumping chamber at the eye of the impeller, said conduit being constantly open, valveless and free from an enlarged liquid supply chamber, said wall partly defining a priming passage leading into the pumping chamber from the lower part of the combined chamber below the surface level of liquid in the casing, said wall also partly defining a flow passage and a discharge passage constituting a progressively enlarged continuation of the flow passage and opening directly into the gas filled part of said combined chamber above the surface of liquid in the casing during the priming operation, the liquid-containing space in the pumping and combined chambers below the intersection of the inlet conduit with the inner surface of the partition exceeding the combined liquidcontaining space in the pumping chamber and in said priming, fluid flow and discharge passages whereby, when the impeller is rotating, the priming, flow and discharge passages will be filled with, and maintained full of, liquid, the rate of flow of liquid discharged from the pumping chamber thereinto will be eifectively decreased in the discharge passage and the flow of unentrained air into the pumping chamber through any of these said passages will be prevented.

References Cited in the file of this patent UNITED STATES PATENTS 1,529,815 Siemen Mar. 17, 1925 1,783,667 Muller Dec. 2, 1930 1,998,266 Brazen Apr. 16, 1935 2,019,143 La Bour Oct. 29, 1935 2,224,615 Stratton Dec. 10, 1940 2,291,760 Rupp Aug. 4, 1942 2,319,230 Harrington May 18, 1943 2,332,875 Stratton Oct. 26, 1943 2,427,307 Schleger Sept. 9, 1947 2,461,925 Rupp Feb. 15, 1949 2,627,812 Mann Feb. 10, 1953 2,627,817 Mann et al. Feb. 10, 1953 FOREIGN PATENTS 645,463 Germany May 28, 1937 

